Currently, heating units, such as fireplaces, are desirable features in the home. Devices that burn non-solid materials, such as gas, or that produce heat electrically have gradually gained popularity. Like wood, the combustion of gas can provide “real” flames, and heat, but oftentimes entails a careful mixing of gas and air for desired or optimal performance, and a realistic flame. This aspect of the gas fireplace, and similar appliances, typically involves the delivery of air for combustion to an arrangement or device where the air is mixed with gaseous fuel, e.g., natural gas (NG) and liquid propane (LP) (“gas”). Clearly, it is advantageous that the air and gas are mixed at a ratio for proper combustion. Then, the mixed air and gas are delivered to a burner element or member, and ultimately provided to a combustion chamber of the fireplace. The mixing of air and gas is oftentimes accomplished in the burner itself.
There has also been a desire by some, such as stores and dealers that sell fireplaces and the like, to have a unit that can operate on different kinds of fuel. In many homes and other buildings, there may be NG or LP available. Sellers may therefore ask for a unit that can be adapted for either NG or LP, depending on what source of gas is available, or desired for the installation. Accordingly, units that may be configured to operate with more than one fuel source were developed. These are typically referred to as “dual-source” or “dual fuel” units. For example, the burner element may include a system that, when in one selected position, allows the unit to operate with a first fuel, and when in a second position, allows the heating unit to operate with a second fuel. These dual-source units are typically set up so that a choice of fuel is made by the installer when the unit is first put into operation. While such dual-source units have been in the art for decades, there is always a desire to make the units simpler to install, safer and more efficient.
Further, different fuels require different conditions to obtain an optimal burn. Such conditions include the amount of oxygen in the burning chamber and the rate of the gas flowing into the burner. Failure to match fuel type to proper burning conditions may result in suboptimal burns and decreased safety. Specifically, an LP gas source allowed to flow through a system metered for NG gas will create a significantly higher burn rate and increased system temperatures than the intended design parameters.